
revolvingBalls :: Behavior Picture
revolvingBalls = overMany [ timeTrans (lift0 (t*pi/4) + time) flashingBall
                            | t <- [0..7] ]
flashingBall = let ball = shape (ell 0.2 0.2) 
               in reg (timeTrans (8*time) flash) 
                      (translate (sin time, cos time) ball)
flash = cond (sin time >* 0) red yellow